Shower base



FIG. 1 is a isometric view of a shower base showing our new design;

FIG. 2 is a front view thereof;

FIG. 3 is a top view thereof;

FIG. 4 is a isometric view of an alternate embodiment of the shower base of FIGS. 1-3;

FIG. 5 is a front view thereof; and,

FIG. 6 is a top view thereof.

The broken line showing of the remainder of the shower base is for environmental purposes and forms no part of the claimed design. 

The ornamental design for a shower base, as shown and described. 